Senator David Vitter (R-La.), top Republican on the Environment and Public Works Committee, and fellow Committee member Senator Jeff Sessions (R-Ala.) in a letter today urged the Environmental Protection Agency (EPA) to review the science behind an economically significant new rule tightening the national ambient air quality standards for fine particulate matter (PM2.5) and to hold off on implementation and enforcement.

"Maybe the biggest reason to slow down the new rule is that the EPA is talking out of both sides of their mouth. On one side exposure to it is deadly, and on the other they say human exposure studies are not harmful," said Vitter. "It's alarming how the EPA is purposefully and blatantly ignoring an ongoing investigation of the legality and therefore scientific legitimacy of the use of human testing. This is another example of the EPA continuing to pick and choose scientific ‘facts' to support their overreaching agenda."

The exposure of human test subjects to diesel exhaust emissions and concentrated airborne particles may have been done without using required protocols and proper consent. In the letter, the Senators noted their concern over EPA's finalizing the PM2.5 rule without the Agency using the "best available science," in addition to ignoring an ongoing EPA Office of Inspector General investigation into whether EPA properly followed applicable laws and procedures in its testing programs.

On December 14, 2012, the Environmental Protection Agency (EPA) announced a new rule tightening the national ambient air quality standards (NAAQS) for fine particulate matter (PM2.5). This is an economically significant regulation, and it is imperative that all federal rules and resulting costs are based on the best science, particularly during this time of slow economic recovery.

We believe there are serious questions that must be addressed before the new PM2.5 NAAQS should be implemented. For instance, we are concerned that EPA proceeded with finalization of these standards notwithstanding an ongoing federal investigation into the underlying science. As you are aware, on October 22, 2012, the EPA Office of Inspector General (OIG) announced that an investigation was underway to determine "whether EPA, as part of its research, followed applicable laws, regulations, policies, procedures, and guidance when it exposed human subjects to diesel exhaust emissions or concentrated airborne particles." EPA apparently conducted or oversaw (or contracted with other entities that have engaged in) human testing programs in an effort to study the impacts of PM2.5 on humans. As part of these experiments, the human subjects were required to sign a waiver that expressly stated that PM2.5 does not pose a serious health risk, even though EPA now contends in its final rule that PM2.5 exposure is deadly.

It is our understanding that the ongoing OIG investigation relates to data relied upon by EPA in its final PM2.5 rule. On page 69 of the final rule, EPA states, "As was true in the last two reviews, evidence from epidemiological, controlled human exposure and animal toxicological studies played a key role in the Integrated Science Assessment's evaluation of the scientific evidence." In other words, it appears that the human clinical studies being investigated by the OIG played a role in the analysis supporting EPA's determination.

Indeed, EPA's own standards for human testing require "the most up-to-date science and the highest ethical standards."[1] To the extent the relevant human exposure studies are determined by the OIG to have deviated from EPA protocol or were otherwise conducted in an improper or unlawful manner, the data cannot be relied upon for regulatory purposes as the "best available science," and it would seem equally clear that the PM2.5 rulemaking would need to be revisited. Notwithstanding the ongoing OIG investigation, EPA and the White House Office of Management & Budget rushed to finalize the new PM2.5 rule after the election without awaiting the OIG's determination.

It is a concern that EPA would assert in the rulemaking process that PM2.5 exposure is deadly while simultaneously asserting in the waivers signed by participants in EPA human exposure studies that these exposures are not harmful. Furthermore, there are valid questions about the quality or usefulness of the exposure studies actually relied upon by EPA. For instance, EPA states on page 282 of the final rule that "the most useful evidence for ... evaluating the distribution of health event data and the corresponding long-term mean PM2.5 concentrations" are short-term exposure studies like Zanobetti and Schwartz (2009) and Bell et al. (2008). However, neither of these studies uses mortality and air quality data more recent than 2005. Moreover, both studies rely upon a limited set of cities and counties, which were selected for unknown reasons. It appears that EPA has so far refused to use more contemporaneous and exhaustive data. For instance, we have recently learned that the California Department of Health has prepared death certificate data for the entire state for the period 1999-2010, and the 2011 mortality data is expected to be available very soon. EPA could, if it desired a comprehensive analysis of recent air quality data for PM2.5, evaluate this California data to determine what relationship, if any, exists between PM2.5 and short-term mortality.

In light of these concerns, we respectfully request a written response from EPA detailing the agency's position with respect to the issues discussed above. We would also urge EPA to hold in abeyance implementation and enforcement of the new PM2.5 NAAQS until:

1. Completion of the OIG investigation and verification by the OIG that these studies complied fully with all applicable laws, regulations, and standards; and

2. Completion of a review of available data current through 2011, including a statistically- and scientifically-sound analysis of recent PM2.5 data for California in comparison to California death certificate analysis.

Air quality is significantly improving in the United States without this costly new regulation; in fact, PM2.5 levels have dropped dramatically over the past decade and good data suggests that this favorable trend will continue without EPA's new PM2.5 standard. Accordingly, we believe there would be no detrimental impact to public health and the environment as a result of granting this request.

Thank you for your kind attention to this matter. We look forward to your response.

Sincerely,

_________________________ ___________________________
David Vitter Jeff Sessions
Ranking Member United States Senator
Environment and Public Works